Lidar laser health diagnostic

ABSTRACT

A sensor diagnostic system includes a first sensor configured to receive a reflected signal that corresponds to a portion of a transmitted signal transmitted from a second sensor and reflected from a surface, a wavelength determination module configured to determine a first wavelength of the reflected signal that is indicative of a second wavelength of the transmitted signal, a wavelength shift detection module configured to determine a shift in at least one of the first wavelength and the second wavelength, and a sensor health analysis module configured to perform diagnostics on the second sensor based on the determined shift.

INTRODUCTION

The information provided in this section is for the purpose of generallypresenting the context of the disclosure. Work of the presently namedinventors, to the extent it is described in this section, as well asaspects of the description that may not otherwise qualify as prior artat the time of filing, are neither expressly nor impliedly admitted asprior art against the present disclosure.

The present disclosure relates to vehicles and more particularly tosystems and methods for performing diagnostics on autonomous drivingsensors.

Vehicles include one or more torque producing devices, such as aninternal combustion engine and/or an electric motor. A passenger of avehicle rides within a passenger cabin (or passenger compartment) of thevehicle.

Autonomous driving systems drive a vehicle completely independent of ahuman driver. For example, autonomous driving systems control theacceleration, brake, and steering systems of a vehicle independent of adriver.

Semiautonomous driving systems drive a vehicle partially independent ofa human driver. For example, a semiautonomous driving system may controlthe steering system independent of a driver while relying on the driverto set a target speed for the semiautonomous driving system to achieveby controlling the acceleration and brake systems.

SUMMARY

A sensor diagnostic system includes a first sensor configured to receivea reflected signal that corresponds to a portion of a transmitted signaltransmitted from a second sensor and reflected from a surface, awavelength determination module configured to determine a firstwavelength of the reflected signal that is indicative of a secondwavelength of the transmitted signal, a wavelength shift detectionmodule configured to determine a shift in at least one of the firstwavelength and the second wavelength, and a sensor health analysismodule configured to perform diagnostics on the second sensor based onthe determined shift.

In other features, the second sensor is a light detection and ranging(LIDAR) sensor.

In other features, the sensor health analysis module is configured todetermine a change in at least one operating characteristic of the LIDARsensor based on the determined shift and perform the diagnostics on theLIDAR sensor based on the determined change in the at least oneoperating characteristic.

In other features, the at least one operating characteristic includes atleast one of a die temperature, mode hopping, optical cavity stability,photon energy, pulse width, power and beam intensity, a shift inmagnitude, a shift in phase, a shift in polarization.

In other features, the sensor health analysis module is configured todetermine the change in the at least one operating characteristic of theLIDAR sensor based on a lookup table correlating the determined shiftwith the change in the at least one operating characteristic.

In other features, the sensor health analysis module is configured toperform the diagnostics of the LIDAR sensor based on a comparisonbetween the change in the at least one operating characteristic and athreshold.

In other features, an autonomous module is configured to selectivelycontrol functions of a vehicle and, based on the diagnostics, one ofdiscontinue controlling functions of the vehicle, disable the LIDARsensor, and activate an indicator.

In other features, the wavelength shift detection module is configuredto determine the shift based on a comparison between the at least one ofthe first wavelength and the second wavelength and a referencewavelength.

In other features, at least one of a spectrometer and aspectroradiometer is configured to determine the first wavelength of thereflected signal.

In other features, the sensor diagnostic system includes a liquidcrystal metasurface.

In other features, the first sensor and the second sensor are arrangedin a passenger cabin of a vehicle.

In other features, the first sensor and the second sensor are arrangedwithin a same housing.

In other features, the first sensor and the second sensor are arrangedin a passenger cabin of the vehicle.

A sensor diagnostic system for a vehicle includes a light detection andranging (LIDAR) sensor that includes a transmitting portion and areceiving portion. The transmitting portion is configured to transmit asignal and the receiving portion is configured to receive, as a receivedsignal, a first portion of the transmitted signal that is reflected froman object in an environment external to the vehicle. A reflected signalsensor is positioned to receive a reflected signal corresponding to asecond portion of the transmitted signal that is reflected from asurface of vehicle. A sensor diagnostic module is configured todetermine a first wavelength of the reflected signal, wherein the firstwavelength is indicative of a second wavelength of the transmittedsignal, determine a shift in at least one of the first wavelength andthe second wavelength, and perform diagnostics on the LIDAR sensor basedon the determined shift.

In other features, the sensor diagnostic module is configured todetermine a change in at least one operating characteristic of the LIDARsensor based on the determined shift and perform the diagnostics on theLIDAR sensor based on the determined change in the at least oneoperating characteristic.

In other features, the at least one operating characteristic includes atleast one of a die temperature, mode hopping, optical cavity stability,photon energy, pulse width, power and beam intensity, a shift inmagnitude, a shift in phase, a shift in polarization.

In other features, the sensor diagnostic module is configured to performthe diagnostics of the LIDAR sensor based on a comparison between thechange in the at least one operating characteristic and a threshold.

In other features, an autonomous module is configured to selectivelycontrol functions of a vehicle and, based on the diagnostics, one ofdiscontinue controlling functions of the vehicle, disable the LIDARsensor, and activate an indicator.

In other features, the sensor diagnostic module is configured todetermine the shift based on a comparison between the at least one ofthe first wavelength and the second wavelength and a referencewavelength.

A method of diagnosing a light detection and ranging (LIDAR) sensor of avehicle includes transmitting a signal, from the LIDAR sensor, from apassenger cabin of the vehicle, receiving, as a received signal, a firstportion of the transmitted signal that passes through a windshield ofthe vehicle and is reflected from an object in an environment externalto the passenger cabin, receiving, using a reflected signal sensorarranged within the passenger cabin of the vehicle, a reflected signalcorresponding to a second portion of the transmitted signal that isreflected from an interior surface within the passenger cabin withoutpassing through the windshield, determining a first wavelength of thereflected signal that is indicative of a second wavelength of thetransmitted signal, determining a shift in at least one of the firstwavelength and the second wavelength, and performing diagnostics on theLIDAR sensor based on the determined shift.

Further areas of applicability of the present disclosure will becomeapparent from the detailed description, the claims and the drawings. Thedetailed description and specific examples are intended for purposes ofillustration only and are not intended to limit the scope of thedisclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure will become more fully understood from thedetailed description and the accompanying drawings, wherein:

FIG. 1 is a functional block diagram of an example vehicle system;

FIG. 2 is a functional block diagram of a vehicle including examples ofexternal sensors and cameras;

FIG. 3 is a functional block diagram of an example sensor diagnosticsystem including a sensor diagnostic module; and

FIG. 4 illustrate steps of an example method of performing diagnosticson a sensor.

In the drawings, reference numbers may be reused to identify similarand/or identical elements.

DETAILED DESCRIPTION

A vehicle may include one or more cameras and/or one or more sensors(i.e., combination transmitter/sensors) used for autonomous driving. Forexample, the sensors may include one or more light detection and ranging(LIDAR) sensors. Systems and methods according to the present disclosureare configured to perform diagnostics (e.g., an assessment ofhealth/functionality) on the sensors. In one example, a sensordiagnostic module detects a wavelength shift of a laser transmitted andreceived by the sensor and diagnoses the sensor based on the wavelengthshift. Various mechanisms may be implemented to measure or estimate thewavelength shift including, but not limited to, a spectrometer, aspectroradiometer, a metasurface (e.g. a liquid crystal (LC)metasurface) arranged to receive/reflect the laser, a prism, mirror,and/or Bragg grating element, etc. Although described with respect tovehicle implementations, the principles of the present disclosure mayalso be applied to non-vehicle implementations or implemented within anyLASER module.

Referring now to FIG. 1, a functional block diagram of an examplevehicle system 100 is presented. While a vehicle system for a hybridvehicle is shown and will be described, the present disclosure is alsoapplicable to non-hybrid vehicles, electric vehicles, fuel cellvehicles, and other types of vehicles.

An engine 102 may combust an air/fuel mixture to generate drive torque.An engine control module (ECM) 106 controls the engine 102. For example,the ECM 106 may control actuation of engine actuators, such as athrottle valve, one or more spark plugs, one or more fuel injectors,valve actuators, camshaft phasers, an exhaust gas recirculation (EGR)valve, one or more boost devices, and other suitable engine actuators.

The engine 102 may output torque to a transmission 110. A transmissioncontrol module (TCM) 114 controls operation of the transmission 110. Forexample, the TCM 114 may control gear selection within the transmission110 and one or more torque transfer devices (e.g., a torque converter,one or more clutches, etc.).

The vehicle system may include one or more electric motors. For example,an electric motor 118 may be implemented within the transmission 110 asshown in the example of FIG. 1. An electric motor can act as either agenerator or as a motor at a given time. When acting as a generator, anelectric motor converts mechanical energy into electrical energy. Theelectrical energy can be, for example, used to charge a battery 126 viaa power control device (PCD) 130. When acting as a motor, an electricmotor generates torque that may be used, for example, to supplement orreplace torque output by the engine 102. While the example of oneelectric motor is provided, the vehicle may include zero or more thanone electric motor.

A power inverter module (PIM) 134 may control the electric motor 118 andthe PCD 130. The PCD 130 applies (e.g., direct current) power from thebattery 126 to the (e.g., alternating current) electric motor 118 basedon signals from the PIM 134, and the PCD 130 provides power output bythe electric motor 118, for example, to the battery 126. The PIM 134 maybe referred to as an inverter module in various implementations.

A steering control module 140 controls steering/turning of wheels of thevehicle, for example, based on driver turning of a steering wheel withinthe vehicle and/or steering commands from one or more vehicle controlmodules. A steering wheel angle sensor (SWA) monitors rotationalposition of the steering wheel and generates a SWA 142 based on theposition of the steering wheel. As an example, the steering controlmodule 140 may control vehicle steering via an EPS motor 144 based onthe SWA 142. However, the vehicle may include another type of steeringsystem.

An electronic brake control module (EBCM) 150 may selectively controlbrakes 154 of the vehicle. Modules of the vehicle may share parametersvia a controller area network (CAN) 162. The CAN 162 may also bereferred to as a car area network. For example, the CAN 162 may includeone or more data buses. Various parameters may be made available by agiven control module to other control modules via the CAN 162.

The driver inputs may include, for example, an accelerator pedalposition (APP) 166 which may be provided to the ECM 106. A cruisecontrol input 168 may also be input to the ECM 106 from a cruise controlsystem. In various implementations, the cruise control system mayinclude an adaptive cruise control system. A brake pedal position (BPP)170 may be provided to the EBCM 150. A position 174 of a park, reverse,neutral, drive lever (PRNDL) may be provided to the TCM 114. An ignitionstate 176 may be provided to a body control module (BCM) 178. Forexample, the ignition state 176 may be input by a driver via an ignitionkey, button, or switch. At a given time, the ignition state 176 may beone of off, accessory, run, or crank.

The vehicle system may include an infotainment module 180. Theinfotainment module 180 controls what is displayed on a display 182. Thedisplay 182 may be a touchscreen display in various implementations andtransmit signals indicative of user input to the display 182 to theinfotainment module 180. The infotainment module 180 may additionally oralternatively receive signals indicative of user input from one or moreother user input devices 184, such as one or more switches, buttons,knobs, etc.

The infotainment module 180 may receive input from a plurality ofexternal sensors and cameras, generally illustrated in FIG. 1 by 186.For example, the infotainment module 180 may display video, variousviews, and/or alerts on the display 182 via input from the externalsensors and cameras 186. The external sensors and cameras 186 mayinclude sensors (e.g., LIDAR sensors) that capture images and videooutside of (external to) the vehicle and various types of sensorsmeasuring parameters outside of (external to) the vehicle. Input fromthe external sensors and cameras 186 may be used to control autonomousdriving.

For example, an autonomous module 188 may be configured to controlsteering, acceleration and deceleration, and braking of the vehicleduring autonomous driving of the vehicle. For example, the autonomousmodule 188 may detect features and objects around the vehicle based oninput from the external cameras and sensors 186 and control steering,acceleration, and deceleration based on the features and objects, suchas to avoid any objects detected. During autonomous driving, however,driver inputs (e.g., steering, braking, and/or acceleration inputs) mayoverride input from the autonomous module 188. The autonomous module 188(and/or another module, such as the ECM 106) according to the presentdisclosure implements a sensor diagnostic module as described below inmore detail.

The infotainment module 180 may also generate output via one or moreother devices. For example, the infotainment module 180 may output soundvia one or more speakers 190 of the vehicle. The vehicle may include oneor more additional control modules that are not shown, such as a chassiscontrol module, a battery pack control module, etc. The vehicle may omitone or more of the control modules shown and discussed.

A global positioning system (GPS) module 192 receives GPS data from aGPS system. A driver monitoring module 194 includes one or more devicesconfigured to monitor one or more characteristics of a driver of thevehicle. For example, the driver monitoring module 194 may include oneor more cameras configured to capture images of the driver and within apassenger cabin of the vehicle, for example, to determine a facialexpression, one or more gestures, hand placement, and other driverinformation based on the images.

A V2X module 196 communicates with other vehicles via a vehicle tovehicle (V2V) communication protocol and/or with infrastructure via avehicle to infrastructure (V2I) communication protocol. V2Vcommunication and V2I communication can be more generally referred to asV2X communication.

Referring now to FIG. 2, a functional block diagram of a vehicle 200including examples of external sensors and cameras (e.g., the externalsensors and cameras 186 as described in FIG. 1) is presented. Theexternal sensors and cameras 186 include various cameras positioned tocapture images and video outside of (external to) the vehicle 200 andvarious types of sensors measuring parameters outside of (external to)the vehicle 200. For example, a forward facing camera 204 capturesimages and video of images within a predetermined field of view (FOV)206 in front of the vehicle 200.

A front camera 208 may also capture images and video within apredetermined FOV 210 in front of the vehicle 200. The front camera 208may capture images and video within a predetermined distance of thefront of the vehicle 200 and may be located at the front of the vehicle200 (e.g., in a front fascia, grille, or bumper). The forward facingcamera 204 may be located more rearward, such as with a rear view mirrorwithin a windshield of the vehicle 200. The forward facing camera 204may not be able to capture images and video of items within all of or atleast a portion of the predetermined FOV of the front camera 208 and maycapture images and video that is greater than the predetermined distanceof the front of the vehicle 200. In various implementations, only one ofthe forward facing camera 204 and the front camera 208 may be included.

A rear camera 212 captures images and video within a predetermined FOV214 behind the vehicle 200. The rear camera 212 may capture images andvideo within a predetermined distance behind the vehicle 200 and may belocated at the rear of the vehicle 200, such as near a rear licenseplate. A right camera 216 captures images and video within apredetermined FOV 218 to the right of the vehicle 200. The right camera216 may capture images and video within a predetermined distance to theright of the vehicle 200 and may be located, for example, under a rightside rear view mirror. In various implementations, the right side rearview mirror may be omitted, and the right camera 216 may be located nearwhere the right side rear view mirror would normally be located. A leftcamera 220 captures images and video within a predetermined FOV 222 tothe left of the vehicle 200. The left camera 220 may capture images andvideo within a predetermined distance to the left of the vehicle 200 andmay be located, for example, under a left side rear view mirror. Invarious implementations, the left side rear view mirror may be omitted,and the left camera 220 may be located near where the left side rearview mirror would normally be located. While the example FOVs are shownfor illustrative purposes, the FOVs may overlap, for example, for moreaccurate and/or inclusive stitching.

The external sensors and cameras 186 also include various other types ofsensors, such as radar sensors, one or more LIDAR sensors 250, etc. Forexample, the vehicle 200 may include one or more forward facing radarsensors, such as forward facing radar sensors 226 and 230, one or morerearward facing radar sensors, such as rearward facing radar sensors 234and 238. The vehicle 200 may also include one or more right side radarsensors, such as right side radar sensor 242, and one or more left sideradar sensors, such as left side radar sensor 246. The locations andfields of view of the cameras and radar sensors are provided as examplesonly and different locations and fields of view could be used. Radarsensors output radar signals around the vehicle 200. Objects around thevehicle 200 can be detected based on input from the external sensors andcameras 186.

One or more sensors may be located rearward of the windshield (e.g.,within the passenger cabin of the vehicle 200, such as the forwardfacing camera 204 as described above). In some examples, a LIDAR sensorincluding a LIDAR transmitter and sensor is located within the passengercabin. Accordingly, a signal transmitted from the LIDAR sensor passesthrough the windshield, reflects off of objects in the environmentexternal to the vehicle, and passes back through the windshield to bereceived by the LIDAR sensor. A portion of the transmitted signal isreflected from an interior surface of the windshield back into thepassenger cabin. The sensor diagnostic module according to the presentdisclosure is configured to perform diagnostics on the transmitter ofthe LIDAR sensor based on the reflected signal as described below inmore detail.

Referring now to FIG. 3, an example sensor diagnostic system 300according to the present disclosure includes a sensor diagnostic module304. The sensor diagnostic module 304 is configured to performdiagnostics on a sensor (e.g., a LIDAR sensor) 308. The sensor 308 isconfigured to transmit a signal (e.g., a laser signal) 312 from withinan interior of a vehicle (e.g., the vehicle 200) through a windshield316 of the vehicle 200. For example, the sensor 308 is arranged in apassenger cabin of the vehicle 200, such as on a ceiling of thepassenger cabin, on or adjacent to a rearview mirror, on a dashboard,etc.

The signal 312 passes through the windshield 316 and is reflected froman object 320 in an environment around the vehicle 200 and is receivedby the sensor 308 as a received signal 324. An autonomous module 328 maydetect features and objects in the environment around the vehicle 200based on input from the sensor 308. For example, the received signal 324indicates a distance between the vehicle 200 and the object 320 and theautonomous module 328 controls functions of the vehicle 200 accordinglyas described above in more detail.

A portion of the signal 312 is reflected off of an interior surface ofthe windshield 316 (as a reflected signal 332) back into the interior ofthe vehicle 200. One or more reflected signal sensors or receivers 336are positioned to receive the reflected signal 332. For example, thereflected signal sensor 336 is arranged in the passenger cabin of thevehicle 200 in a location corresponding to a known or predeterminedtrajectory of the reflected signal 332, such as on a ceiling of thepassenger cabin, on or adjacent to the rearview mirror, on thedashboard, etc. In some examples, the reflected signal sensor 336 islocated adjacent to or integrated within the sensor 308 (e.g.,integrated within a same housing as the sensor 308). The trajectory ofthe reflected signal 332 may be dependent upon the rake or angle of thewindshield 316, a material composition of the windshield 315, etc.Accordingly, the trajectory of the reflected signal 332 and the locationof the reflected signal sensor 336 may vary by vehicle. In someexamples, the windshield 316 may include an embedded or attachedreflecting module (not shown) positioned to receive and reflect thesignal 312 at a predetermined trajectory (i.e., toward a desiredposition of the reflected signal sensor 336).

In some examples, a liquid crystal metasurface may be arranged toreceive the signal 312 or the reflected signal 332. For example, theliquid crystal metasurface may be arranged adjacent to or embeddedwithin the windshield 316 and may be configured to receive the signal312 and steer one or more of the reflected signals 332 in a desireddirection. In other examples, the reflected signal sensor 336 mayinclude a liquid crystal metasurface configured to receive the reflectedsignal 332. In still other examples, the liquid crystal metasurface maybe arranged elsewhere within the passenger cabin, within the sensor 308,etc.

The sensor diagnostic module 304 is configured to perform diagnostics onthe sensor 308 (e.g., a transmitter portion of the sensor 308) based onthe reflected signal 332. For example, the sensor diagnostic module 304receives an output 340 of the reflected signal sensor 336 indicative ofcharacteristics of the reflected signal 332. The sensor diagnosticmodule 304 is configured to determine a wavelength of the reflectedsignal 332, which is indicative of a wavelength of the signal 312transmitted from the sensor 308. The sensor diagnostic module 304determines (diagnoses) a condition of the sensor 308 based on thedetermined wavelength of the reflected signal 332.

For example, the sensor diagnostic module 304 includes a wavelengthdetermination module 344 configured to determine the wavelength of thereflected signal 332 and, correspondingly, the wavelength of the signal312 based on the output 340 of the reflected signal sensor 336. Forexample, the reflected signal sensor 336 and the wavelengthdetermination module 344 may correspond to components of a chip-scalespectrometer configured to receive the reflected signal 332, measure thewavelength of the reflected signal 332, and output a wavelength signal348 indicating the measured wavelength. In another example, thereflected signal sensor 336 and/or the wavelength determination module344 may include components including, but not limited to, a prism, aBragg deflector or grating element, a beam combiner, fiber optic cablesand couplings, etc. configured to receive the reflected signal 332,measure the wavelength of the reflected signal 332, and output thewavelength signal 348.

In one example, the wavelength signal 348 may correspond to thewavelength of the reflected signal 332. In another example, thewavelength determination module 344 determines the wavelength of thesignal 312 based on the measured wavelength of the reflected signal 332and the wavelength signal 348 corresponds to the wavelength of thesignal 312.

A wavelength shift detection module 352 receives the wavelength signal348 and calculates a wavelength shift based on changes in the wavelengthsignal 348. For example, the wavelength shift detection module 352 isconfigured to compare the wavelength signal 348 with a referencewavelength. The reference wavelength may correspond to a wavelength ofthe transmitted signal 312 during normal operation. The referencewavelength may be determined during manufacture, measured duringcalibration of the sensor 308, determined over time during an operationperiod of the sensor 308, etc. The wavelength shift detection module 352outputs a wavelength shift signal 356 indicative of the calculatedwavelength shift.

A sensor health analysis module 360 receives the wavelength shift signal356 and is configured to perform diagnostics on the sensor 308 based onthe wavelength shift signal 356. The wavelength of the signal 312 (and,correspondingly, the wavelength shift indicated by the wavelength shiftsignal 356) is indicative of various operating characteristics of thesensor 308, which may be further indicative of the health of the sensor308.

For example, the wavelength of the signal 312 may indicate operatingcharacteristics of the sensor 308 including, but not limited to, a dietemperature of the sensor 308, mode hopping, optical cavity stability,photon energy, pulse width, power and beam intensity, and shifts inmagnitude, phase, and/or polarization. In other words, the wavelengthshift indicates a corresponding change in respective operatingcharacteristics of the sensor 308. Respective relationships between thewavelength shift and the changes in the operating characteristics of thesensor 308 may vary by laser type and in accordance with other operatingor environmental characteristics (e.g., temperature). For example, dietemperature may have a generally linear or piecewise linear relationshipwith the wavelength of the signal 312. For example only, the sensorhealth analysis module 360 may determine the changes in the operatingcharacteristics of the sensor 308 using a lookup table that correlateswavelength shift to changes in the respective operating characteristics,respective formulas or algorithms that use wavelength shift as an inputto calculate the operating characteristics, models, etc.

The sensor health analysis module 360 is configured to selectivelycommand and/or perform one or more remedial actions based on thewavelength shift and corresponding changes to the operatingcharacteristics. For example, the sensor health analysis module 360outputs a diagnostic result signal 364 requesting one or more remedialactions. For example only, the diagnostic result signal 364 may indicatethat the wavelength shift and/or changes in one or more of the operatingcharacteristics of the sensor 308 exceeds a respective threshold.

In some examples, the sensor health analysis module 360 may beconfigured to predict degradation and/or a remaining lifetime of thesensor 308. For example, as the wavelength shift varies or increasesover time, the sensor health analysis module 360 may predict (e.g.,based on a rate of change of the wavelength) when the wavelength shiftwill reach a threshold indicating that the sensor 308 is no longerreliable.

The autonomous module 328 may receive the diagnostic result signal 364and selectively perform remedial actions based on the diagnostic resultsignal 364. The remedial actions include, but are not limited to,activating an indicator to inform a driver of the health of the sensor308 (e.g., activing a check engine or other diagnostic light, displayinginformation on a display screen, etc.), deactivating the sensor 308,disregarding inputs received from the sensor 308, disabling autonomousdriving functions, etc.

FIG. 4 is an example method 400 of performing diagnostics on a sensor308 according to the principles of the present disclosure. At 404, themethod 400 transmits a signal from a sensor (e.g., transmits a laserfrom a LIDAR sensor, such as the signal 312 transmitted from the sensor308). At 408, the method 400 (e.g., the reflected signal sensor 336)receives a portion of the signal reflected from a surface, such as aninterior surface of the windshield 316. At 412, the method 400 (e.g.,respective components of the reflected signal sensor 336 and/or thewavelength determination module 344) determines and outputs a wavelengthof the reflected signal and/or the wavelength of the transmitted signal.

At 416, the method 400 (e.g., the wavelength shift detection module 352)determines and outputs a wavelength shift of the reflected signal and/orthe transmitted signal. At 420, the method 400 (e.g., the sensor healthanalysis module 360) performs diagnostics on the sensor 308 based on thewavelength shift. For example, the sensor health analysis module 360determines changes in operating characteristics of the sensor 308 basedon the wavelength shift and performs the diagnostics based on thechanges in the operating characteristics.

At 424, the method 400 (e.g., the sensor health analysis module 260, theautonomous module 328, etc.) determines whether to perform one or moreremedial actions based on the diagnostics. For example, the method 400determines whether one or more of the wavelength shift and the operatingcharacteristics exceeds a respective threshold indicative of degradedperformance (e.g., inaccurate sensing results). If true, the method 400continues to 428. If false, the method 400 continues to 404.

At 428, the method 400 (e.g., the sensor health analysis module 260, theautonomous module 328, etc.) selectively performs one or more remedialactions based on the diagnostics. The method 400 then continues to 404.Accordingly, the method 400 may continuously (or, in some examples,periodically, conditionally, etc.) monitor the reflected signal 332 todiagnose the health of the sensor 308.

The foregoing description is merely illustrative in nature and is in noway intended to limit the disclosure, its application, or uses. Thebroad teachings of the disclosure can be implemented in a variety offorms. Therefore, while this disclosure includes particular examples,the true scope of the disclosure should not be so limited since othermodifications will become apparent upon a study of the drawings, thespecification, and the following claims. It should be understood thatone or more steps within a method may be executed in different order (orconcurrently) without altering the principles of the present disclosure.Further, although each of the embodiments is described above as havingcertain features, any one or more of those features described withrespect to any embodiment of the disclosure can be implemented in and/orcombined with features of any of the other embodiments, even if thatcombination is not explicitly described. In other words, the describedembodiments are not mutually exclusive, and permutations of one or moreembodiments with one another remain within the scope of this disclosure.

Spatial and functional relationships between elements (for example,between modules, circuit elements, semiconductor layers, etc.) aredescribed using various terms, including “connected,” “engaged,”“coupled,” “adjacent,” “next to,” “on top of,” “above,” “below,” and“disposed.” Unless explicitly described as being “direct,” when arelationship between first and second elements is described in the abovedisclosure, that relationship can be a direct relationship where noother intervening elements are present between the first and secondelements, but can also be an indirect relationship where one or moreintervening elements are present (either spatially or functionally)between the first and second elements. As used herein, the phrase atleast one of A, B, and C should be construed to mean a logical (A OR BOR C), using a non-exclusive logical OR, and should not be construed tomean “at least one of A, at least one of B, and at least one of C.”

In the figures, the direction of an arrow, as indicated by thearrowhead, generally demonstrates the flow of information (such as dataor instructions) that is of interest to the illustration. For example,when element A and element B exchange a variety of information butinformation transmitted from element A to element B is relevant to theillustration, the arrow may point from element A to element B. Thisunidirectional arrow does not imply that no other information istransmitted from element B to element A. Further, for information sentfrom element A to element B, element B may send requests for, or receiptacknowledgements of, the information to element A.

In this application, including the definitions below, the term “module”or the term “controller” may be replaced with the term “circuit.” Theterm “module” may refer to, be part of, or include: an ApplicationSpecific Integrated Circuit (ASIC); a digital, analog, or mixedanalog/digital discrete circuit; a digital, analog, or mixedanalog/digital integrated circuit; a combinational logic circuit; afield programmable gate array (FPGA); a processor circuit (shared,dedicated, or group) that executes code; a memory circuit (shared,dedicated, or group) that stores code executed by the processor circuit;other suitable hardware components that provide the describedfunctionality; or a combination of some or all of the above, such as ina system-on-chip.

The module may include one or more interface circuits. In some examples,the interface circuits may include wired or wireless interfaces that areconnected to a local area network (LAN), the Internet, a wide areanetwork (WAN), or combinations thereof. The functionality of any givenmodule of the present disclosure may be distributed among multiplemodules that are connected via interface circuits. For example, multiplemodules may allow load balancing. In a further example, a server (alsoknown as remote, or cloud) module may accomplish some functionality onbehalf of a client module.

The term code, as used above, may include software, firmware, and/ormicrocode, and may refer to programs, routines, functions, classes, datastructures, and/or objects. The term shared processor circuitencompasses a single processor circuit that executes some or all codefrom multiple modules. The term group processor circuit encompasses aprocessor circuit that, in combination with additional processorcircuits, executes some or all code from one or more modules. Referencesto multiple processor circuits encompass multiple processor circuits ondiscrete dies, multiple processor circuits on a single die, multiplecores of a single processor circuit, multiple threads of a singleprocessor circuit, or a combination of the above. The term shared memorycircuit encompasses a single memory circuit that stores some or all codefrom multiple modules. The term group memory circuit encompasses amemory circuit that, in combination with additional memories, storessome or all code from one or more modules.

The term memory circuit is a subset of the term computer-readablemedium. The term computer-readable medium, as used herein, does notencompass transitory electrical or electromagnetic signals propagatingthrough a medium (such as on a carrier wave); the term computer-readablemedium may therefore be considered tangible and non-transitory.Non-limiting examples of a non-transitory, tangible computer-readablemedium are nonvolatile memory circuits (such as a flash memory circuit,an erasable programmable read-only memory circuit, or a mask read-onlymemory circuit), volatile memory circuits (such as a static randomaccess memory circuit or a dynamic random access memory circuit),magnetic storage media (such as an analog or digital magnetic tape or ahard disk drive), and optical storage media (such as a CD, a DVD, or aBlu-ray Disc).

The apparatuses and methods described in this application may bepartially or fully implemented by a special purpose computer created byconfiguring a general purpose computer to execute one or more particularfunctions embodied in computer programs. The functional blocks,flowchart components, and other elements described above serve assoftware specifications, which can be translated into the computerprograms by the routine work of a skilled technician or programmer.

The computer programs include processor-executable instructions that arestored on at least one non-transitory, tangible computer-readablemedium. The computer programs may also include or rely on stored data.The computer programs may encompass a basic input/output system (BIOS)that interacts with hardware of the special purpose computer, devicedrivers that interact with particular devices of the special purposecomputer, one or more operating systems, user applications, backgroundservices, background applications, etc.

The computer programs may include: (i) descriptive text to be parsed,such as HTML (hypertext markup language), XML (extensible markuplanguage), or JSON (JavaScript Object Notation) (ii) assembly code,(iii) object code generated from source code by a compiler, (iv) sourcecode for execution by an interpreter, (v) source code for compilationand execution by a just-in-time compiler, etc. As examples only, sourcecode may be written using syntax from languages including C, C++, C#,Objective-C, Swift, Haskell, Go, SQL, R, Lisp, Java®, Fortran, Perl,Pascal, Curl, OCaml, Javascript®, HTML5 (Hypertext Markup Language 5threvision), Ada, ASP (Active Server Pages), PHP (PHP: HypertextPreprocessor), Scala, Eiffel, Smalltalk, Erlang, Ruby, Flash®, VisualBasic®, Lua, MATLAB, SIMULINK, and Python®.

What is claimed is
 1. A sensor diagnostic system, comprising: a firstsensor configured to receive a reflected signal, wherein the reflectedsignal corresponds to a portion of a transmitted signal transmitted froma second sensor and reflected from a surface; a wavelength determinationmodule configured to determine a first wavelength of the reflectedsignal, wherein the first wavelength is indicative of a secondwavelength of the transmitted signal; a wavelength shift detectionmodule configured to determine a shift in at least one of the firstwavelength and the second wavelength; and a sensor health analysismodule configured to perform diagnostics on the second sensor based onthe determined shift.
 2. The sensor diagnostic system of claim 1,wherein the second sensor is a light detection and ranging (LIDAR)sensor.
 3. The sensor diagnostic system of claim 2, wherein the sensorhealth analysis module is configured to determine a change in at leastone operating characteristic of the LIDAR sensor based on the determinedshift and perform the diagnostics on the LIDAR sensor based on thedetermined change in the at least one operating characteristic.
 4. Thesensor diagnostic system of claim 3, wherein the at least one operatingcharacteristic includes at least one of a die temperature, mode hopping,optical cavity stability, photon energy, pulse width, power and beamintensity, a shift in magnitude, a shift in phase, a shift inpolarization.
 5. The sensor diagnostic system of claim 3, wherein thesensor health analysis module is configured to determine the change inthe at least one operating characteristic of the LIDAR sensor based on alookup table correlating the determined shift with the change in the atleast one operating characteristic.
 6. The sensor diagnostic system ofclaim 3, wherein the sensor health analysis module is configured toperform the diagnostics of the LIDAR sensor based on a comparisonbetween the change in the at least one operating characteristic and athreshold.
 7. The sensor diagnostic system of claim 3, furthercomprising an autonomous module configured to (i) selectively controlfunctions of a vehicle and (ii) based on the diagnostics, one ofdiscontinue controlling functions of the vehicle, disable the LIDARsensor, and activate an indicator.
 8. The sensor diagnostic system ofclaim 1, wherein the wavelength shift detection module is configured todetermine the shift based on a comparison between (i) the at least oneof the first wavelength and the second wavelength and (ii) a referencewavelength.
 9. The sensor diagnostic system of claim 1, furthercomprising at least one of a spectrometer and a spectroradiometerconfigured to determine the first wavelength of the reflected signal.10. The sensor diagnostic system of claim 1, further comprising a liquidcrystal metasurface.
 11. The sensor diagnostic system of claim 1,wherein the first sensor and the second sensor are arranged in apassenger cabin of a vehicle.
 12. The sensor diagnostic system of claim1, wherein the first sensor and the second sensor are arranged within asame housing.
 13. A vehicle comprising the sensor diagnostic system ofclaim 1, wherein the first sensor and the second sensor are arranged ina passenger cabin of the vehicle.
 14. A sensor diagnostic system for avehicle, the sensor diagnostic system comprising: a light detection andranging (LIDAR) sensor, wherein the LIDAR sensor includes a transmittingportion and a receiving portion, wherein the transmitting portion isconfigured to transmit a signal, and wherein the receiving portion isconfigured to receive, as a received signal, a first portion of thetransmitted signal that is reflected from an object in an environmentexternal to the vehicle; a reflected signal sensor positioned to receivea reflected signal corresponding to a second portion of the transmittedsignal that is reflected from a surface of vehicle; and a sensordiagnostic module configured to (i) determine a first wavelength of thereflected signal, wherein the first wavelength is indicative of a secondwavelength of the transmitted signal, (ii) determine a shift in at leastone of the first wavelength and the second wavelength, and (iii) performdiagnostics on the LIDAR sensor based on the determined shift.
 15. Thesensor diagnostic system of claim 14, wherein the sensor diagnosticmodule is configured to determine a change in at least one operatingcharacteristic of the LIDAR sensor based on the determined shift andperform the diagnostics on the LIDAR sensor based on the determinedchange in the at least one operating characteristic.
 16. The sensordiagnostic system of claim 15, wherein the at least one operatingcharacteristic includes at least one of a die temperature, mode hopping,optical cavity stability, photon energy, pulse width, power and beamintensity, a shift in magnitude, a shift in phase, a shift inpolarization.
 17. The sensor diagnostic system of claim 15, wherein thesensor diagnostic module is configured to perform the diagnostics of theLIDAR sensor based on a comparison between the change in the at leastone operating characteristic and a threshold.
 18. The sensor diagnosticsystem of claim 15, further comprising an autonomous module configuredto (i) selectively control functions of a vehicle and (ii) based on thediagnostics, one of discontinue controlling functions of the vehicle,disable the LIDAR sensor, and activate an indicator.
 19. The sensordiagnostic system of claim 14, wherein the sensor diagnostic module isconfigured to determine the shift based on a comparison between (i) theat least one of the first wavelength and the second wavelength and (ii)a reference wavelength.
 20. A method of diagnosing a light detection andranging (LIDAR) sensor of a vehicle, the method comprising: transmittinga signal, from the LIDAR sensor, from a passenger cabin of the vehicle;receiving, as a received signal, a first portion of the transmittedsignal that passes through a windshield of the vehicle and is reflectedfrom an object in an environment external to the passenger cabin;receiving, using a reflected signal sensor arranged within the passengercabin of the vehicle, a reflected signal corresponding to a secondportion of the transmitted signal that is reflected from an interiorsurface within the passenger cabin without passing through thewindshield; determining a first wavelength of the reflected signal,wherein the first wavelength is indicative of a second wavelength of thetransmitted signal; determining a shift in at least one of the firstwavelength and the second wavelength; and performing diagnostics on theLIDAR sensor based on the determined shift.